Oil noise baffle



Nov. 25, 1969 w. HATTEN OIL NOISE BAFFLE Filed Nov. 29, 1967 INVENTORBernard W. Hutten WITNESSES:

ATTORNEY United States Patent 3,480,205 OIL NOISE BAFFLE Bernard W.Hatten, Columbus, Ohio, assignor to Westinghouse Electric Corporation,Pittsburgh, Pa., 21 corporation of Pennsylvania Filed Nov. 29, 1967,Ser. No. 686,513 Int. Cl. F04b 35/04, 39/02 U.S. Cl. 230-232 5 ClaimsABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION Motor compressorunits, of the type to which the present invention relates, have found awide field of usage in domestic appliances; for example, domesticrefrigerators, freezers and room air conditioners. With motor compressorrefrigeration units for domestic appliances, improvements which reducenoise from the units are of prime importance.

Various features and improvements have been utilized to reduce noiselevels in motor compressor units. One of the important beingpresentlyiutilized is the resilient mounting of the motor compressorunit within the hermetically-sealed shell which surrounds and houses theunit. Prior to use of the resilient mounting, the motor compressor unitwas secured directly and rigidly to the shell structure with the resultthat all noises emanating from within the unit were transmitted directlyand immediately to the shell and from the latter to the appliancegenerally. The resilient mounting resulted in a substantial reduction intransmission of noise from the motor compressor unit to the shell onwhich it was resiliently mounted.

However, it was found that the body of liquid lubricant which ismaintained within the unit shell served as a sound-transmitting mediumwhere any portion of the motor compressor unit was submerged in thelubricant, as is frequently the situation in such devices. This problemwas alleviated to a considerable and practical extent by aerating thelubricant to reduce its sound transmitting capabilities (see for examplePatent No. 3,155,312 in the name of Richard T. Douglas granted Nov. 3,1964 and assigned to the assignee of the present application).

It is believed that the type of aerating device most commonly used atpresent is a mechanical stirrer attached to and driven by the verticallydisposed motor shaft, the stirrer extending into the body of lubricantin the lower portion of the shell and during rotation serving to mix thelubricant with the air and/or gases present in the shell above thelubricant to provide a foam of the lubricant and gas which serves toreduce the sound transmitting abilities of the lubricant body.

It has also been found that where this stirrer is not more or lesssurrounded by portions of the motor compressor unit extending into thebody of lubricant in the horizontal plane of the stirrer, there may beproduced a sloshing noise apparently resulting from flow of lubricantfrom the stirrer to the sidewalls of the shell or in the reversedirection from the shell sidewalls to the stirrer, probably dependingupon the particular design of impeller utilized.

It is an object of the present invention to provide, in a motorcompressor shell assembly of the type discussed above, a bafilestructure surrounding the stirrer to reduce or eliminate such flow oflubricant between the stirrer and the shell wall as has heretoforeproduced the objectionable sloshing noise.

SUMMARY OF THE INVENTION In accordance with the present invention, thestirrer which produces aeration of the body of lubricant is surrounded,in whole or in part, by a baffie of generally cylindrical shape andcarried by either the motor-compressor unit itself (in which case itpreferably extends downwardly into the oil bath in the generalhorizontal plane of the impeller), or is carried by the shell bottom orlower sidewalls and extends upwardly therefrom into the oil bath, againin the general horizontal plane of the stirrer. It may be founddesirable to perforate this baflle to a degree suflicient to permitrestricted flow of lubricant from one side to the other of the bafilestructure.

DRAWING DESCRIPTION Various objects, features, and advantages of theinvention will appear more fully from the detailed description whichfollows, taken in connection with the accompanying drawings, forming apart of this application, in which:

The single figure is a vertical sectional side view of the hermeticallysealed shell, with portions of the shell eliminated to reveal intrenalportions of the motor compressor unit, portions of latter being shown incrosssection.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the single figure, thereference character 10 indicates, in its entirety, anhermetically-sealed motor-compressor refrigeration unit comprising anhermetically-sealed shell 11 housing an electric motor 12 adapted todrive a piston type compressor 13 disposed therebelow with the motoroperating about a vertical axis and the compressor piston reciprocatingin a horizontal path.

The compressor 13 includes a housing 14 in which the piston 16reciprocates, the latter being driven by a connecting rod 17 havingdriving connection with an eccentric 18 formed adjacent the lower end ofthe motor shaft 19.

Carried by the lowermost end of the motor shaft 19 is a stirrer 21having one or more arms 22 extending into a body 23 of liquid lubricant,disposed in the lower portion of the space enclosed by thehermetically-sealed shell 11. The structure so far described may beconsidered as typical of prior art devices of this general character.

A baflle 26, herein disclosed as generally annular or cylindrical, issecured to the underside of the compressor housing 14, and extendsdownwardly into the body of lubricant 23, well below the surfacethereof. Preferably, this bafile is provided with a plurality ofperforations 27, which permit limited flow of lubricant from one side tothe other of the cylindrical or annular bafile 26. -It will be notedthat this baffle extends in the same general horizontal plane as do thearms 22 of the stirrer 21 with a result that any miniature waves whichmight otherwise be established and perpetuated by the stirrer areinterrupted in their flow between the impeller and the sidewalls of theshell 11.

There is also provided a second bafile 28, also annular in formation,extending upwardly from the bottom wall of the shell 11 into the regionof the stirrer arms 22. It will be noted that these two bafiles 26 and28 overlap slightly in axial directions. It should further be apparentthat either baflle could be omitted and the retained baflle extendedvertically to any extent found desirable. That is, the upper bafile 26could extend downwardly almost into contact with the shell bottom wallor the lower bafile 28 could be extended upwardly to or above thesurface of the lubricant body 23. The only limitation with respect tovertical extent of these bafiies would be that the upper bafile 26should not extend downwardly into contact with the shell bottom wall norshould the lower baffle 28 extend upwardly sufficiently far to becontacted by the compressor housing 14 as such contact by either baifiewould result in direct transmission of noise from the motorcompressorunit to the shell.

It is believed clear that, in the construction illustrated, if thebafiles 26 and 28 were omitted, miniature waves could be set up in thebody of lubricant by the stirrer, which waves would produce anobjectionable sloshing sound, readily transmitted to the shell 11. Theprovision of the herein disclosed bafiies, either singly or incombination, are found to provide satisfactory reduction in, orelimination of, objectionable sloshing noises.

While the invention has been shown in but one form, it will be apparentto those skilled in the art that it is not so limited, but issusceptible of various changes and modifications without departing fromthe spirit thereof.

I claim:

1. Refrigeration apparatus comprising a motor-compressor unit,

a sealed shell housing said unit,

a body of liquid lubricant in said shell,

means resiliently mounting said unit in said shell in spaced relation tothe latter,

means for aerating said body of lubricant to reduce the ability of thelatter to transmit noise from the unit to the shell, and

means for limiting movement of said lubricant towards and away from thevicinity of said aerating means to reduce sloshing noise, said means forlimiting movement of lubricant comprises a first baflie structure atleast partially surrounding said aerating means and extending upwardlyfrom the shell bottom.

2. Structure according to claim 1 wherein said means for limitingmovement of lubricant also includes a second bafiie structure at leastpartially surrounding said aerating means and extending downwardly fromthe motor-compressor unit.

3. Structure according to claim 1 wherein said aerating means comprisesa stirrer.

4. Structure according to claim 1 wherein at least one of said bafiiestructures is provided with perforations to permit limited flow oflubricant from one side of said bafile structure to the other side.

5. Structure according to claim 1 wherein said first and second bafiiestructures overlap in the axial direction.

ROBERT M. WALK'ER, Primary Examiner U.S. Cl. X.R. 23058, 206

